7.1.1.  Urban Plan Communication

Communicating new developments and masterplans to the public.

Required Modules: Buildings

Benefititial Modules: Appearance

LOD: High

7.1.2.  Urban Planning / Comprehensive Planning

Overview of projects accross cities (permiting building status) SOR of planned projects

Manage KPIs such as GFA Mix, FAR etc.

To guide the long-term development of urban areas, balancing land use, infrastructure, and environmental sustainability. To assess and optimize the spatial arrangement of residential, commercial, industrial, and recreational areas, as well as transportation networks, utilities, and green spaces. In urban planning, the focus is on developing strategies to manage the growth and development of cities in a way that meets the needs of current and future populations while ensuring environmental sustainability. This involves comprehensive planning of land use, zoning, transportation, and the integration of various urban systems. The use of 3D models aids planners in visualizing the entire urban environment, understanding how different components interact, and simulating potential outcomes of different planning scenarios. This allows for informed decision-making and helps in balancing competing needs like housing, infrastructure, and green space.

Relevant thematic modules in CityGML for this use case include:

Building (for the visualization and analysis of existing and planned buildings, their heights, densities, and potential land use) LandUse (to manage and plan the zoning of different areas for residential, commercial, industrial, and recreational purposes) Transportation (to model transportation networks, including roads, railways, and public transport systems, supporting planning of efficient movement and connectivity) Relief (to incorporate topography and terrain data, which influences planning decisions related to construction, drainage, and infrastructure) Vegetation (to plan and integrate green spaces, parks, and tree coverage within urban areas, promoting sustainability and enhancing quality of life) CityFurniture (to plan the placement of urban elements such as benches, lighting, and public facilities that improve the livability of spaces)

7.2.1.  Sight & Shadow Analyis

7.2.2.  Solar Potential & Solar Irradiance

The estimation of the solar potential for roofs and facades is an often cited application for 3D City Models and many cities …​.

7.2.3.  Daylight Simulations

In some countries, Daylight simulations are part of the urban planning or building permit process.

The latter is usually conducted using architectural tools, using a detailed 3D model of the building in question (i.e. BIM) and less detailed models of the surrounding context. In this case, the 3D City Model only serves as a source for context and does not require detailed information on rooms or windows.

The first case typically includes the calculation of solar irradiation at window level of surrounding buildings. This requires information about the position and size of the the windows. Currently, most cities do not have this information available for existing (older) buildings.

Relevant Modules: Buildings Required Information: Windows

7.2.4.  Noise Simulation

Noise Simulations become increasingly important as part of the urban planning process. The simulation input is usually noise sources and obstacles from which the propagation of noise is calculated.

3D City models are a useful foundation for the calculation of noise propagation as they include physical obstacles (buildings, sound barriers, vegetation) and potentially also include information about the acoustic properties of horizontal and vertical surfaces (hard vs soft surfaces).

While possible (i.e. Dynamizers) Noise sources are usually not stored as part of the 3D City Model and are derived from other sources (i.e. road database, which includes speed limits, surface material and traffic count).

The calculation of the noise propagation is performed in a dedicated software. An ETL process, combining different sources and preparing a suitable input format for the software is required. For performance benefits, a lower LOD of the city model is usually preferred.

→ requires semantic information about hard vs soft surfaces → requires informatio about speed limit etc on street → external reference

Relevant Modules: Building, Vegetation, Transport, CityFurniture (Walls), Relief? Relevant Properties: Acoustic Surface Properties

7.2.5.  Flood Simulation

In some locations, flood simulations are an essential part of urban planning and emergency precaution.

The main input to the simulations are terrain and 3D objects (i.e. buildings). For more accurate calculations, information on ground roughness and infiltration capacity (permeable vs impermeable) are required.

While the simulation could theoretically be ran on a 3D City Model, the common hydorological models and simulation softwares rely on homogenous and continous raster DTMs as input.

These are in practice derived from a rasterized top view of the 3D objects (i.e. Buildings) combined with a DTM and (if applicable) additional raster layers describing surface coverage and permeability.

Required Modules: Building, CityFurniture, Relief Optional Modules: Vegetation

7.2.6.  Urban Climate Indicators

This use case is commonly applied in urban design and planning to understand the environmental effects of urban form, building materials, vegetation, and street layout. The simulation typically models how elements like building density, orientation, and green spaces influence the local microclimate, such as heat distribution, airflow, and sunlight exposure. By analyzing the interaction between buildings and the surrounding environment, urban planners can identify areas susceptible to overheating, poor air circulation, or uncomfortable wind conditions, enabling them to design more climate-resilient urban spaces.

Relevant thematic modules in CityGML for this use case include:

*Transportation (to model roads and their effect on urban heat islands and airflow)

7.3.1.  First Response (Indoor )

Relevant thematic modules in CityGML for this use case include:

Building (to provide detailed 3D geometry of building structures, including rooms, corridors, staircases, and entry/exit points, which is essential for navigation during emergencies) BuildingPart (to represent individual floors, rooms, and sections of a building, enabling responders to locate specific areas and identify potential hazards such as storage rooms or chemical hazards) BuildingInstallation (to include critical infrastructure like fire alarms, sprinkler systems, ventilation shafts, and electrical panels that need to be accessed or disabled during a fire emergency) CityFurniture (to map exterior elements like hydrants, access points, and street furniture that aid in emergency response outside the building) Relief (to incorporate terrain and topography information that can influence accessibility to the building, especially in multi-story or uneven terrain environments)

7.3.2.  Facility Management of Buildings

This Use Case is not in the scope of this Best Practice as it focuses on single buildings. While it is theoretically possible to use CityGML, it is recommended to rely on BIM (IFC) models for this use case. While CityGML is focused on urban scale and context, IFC is better suited for managing the detailed, technical data required during construction and lifecycle management of buildings.

7.3.3.  3D Cadastre

In the context of 3D cadastre, the goal is to extend traditional 2D land registries to include the full vertical and underground dimensions of urban space. This is especially relevant in dense urban environments, where buildings, utilities, and infrastructure often span multiple levels or go underground. The 3D cadastre use case supports the creation of legal and ownership boundaries for both above-ground and sub-surface spaces, such as air rights, underground utilities, and property extensions like balconies or rooftops. It also aids in resolving conflicts between adjacent properties and facilitating the legal management of complex land use scenarios.

Relevant thematic modules in CityGML for this use case include:

Optional/TBD * Transportation (for defining rights of way and boundaries of roads or public transportation infrastructure that may intersect or overlap with private properties)

8.2.1.  Building Module

Applications must partially support the buildings module to comply with this profile.

Recommended classes:

Building & Building Part Applications shall support the TopLevelFeatureType “Building” as well as the FeatureType “BuildingPart”.

Storeys & Rooms Applications may support the FeatureTypes “BuildingRoom”, “BuildingUnit” and “Storeys”

Not recommended classes:

Building Installation & Furniture Applications may support the FeatureTypes “BuildingInstallation”, “BuildingUnit” and “Storeys”

Constructive Elements Applications may support the FeatureTypes “BuildingContructiveElements”,

Figure 1 — UML of Building Module

8.2.2.  Bridge Module

Figure 2

8.2.3.  Vegetation Module

 

Figure 3-1

===

==== CityFurniture Module

=== Optional Modules

==== Tunnel Module .UML of Tunnel Module image::./figures/UML_Tunnel.bmp[height=150]

==== Construction Module The support of the "Constructions""module is not required for compliance with this profile.

→ better to use alternatives/ifc → no use cases that warrent the query of individual surfaces / constructive elements accross city

==== Construction Module The support of the "CityObjectGroup""module is not required for compliance with this best practice.

 

Figure 3-2 — UML of Construction Module

==== Relief

• Tin: Support is impractical due to constraints with Delaunay triangulation.

• RasterRelief: TINRelief/TriangulatedSurface is supported; alternatives for unsupported formats are suggested.

→ in practice often from different source, also dedicated formats

==== Land Use

==== Water Body

==== Tunnel Module

==== Generics Module

==== Transportation Module

→ recommended to use dedicated systems?

==== Appearance The support of the "Constructions""module is not required for compliance with this profile.

→ alternatives way of storing textures?? also reality meshes

=== Excluded Modules Excluded from this profile. The following modules are not considered in the context of this best practice document.

==== Versioning The Versioning module is excluded from the scope of this profile. It is recommended to rely on a external version control (git) or database system to handle version control.

==== Point Cloud The Point Cloud module is excluded from the scope of this profile. It is recommended to use optimized storage formats and systems for point clouds.

==== Dynamizer The Versioning module is excluded from the scope of this profile. It is recommended to rely on dedicated systems / records for this kind of data.

=== Geometry Objects ==== Geometry Types The CityGML Conceptual Model does not put any restriction on the usage of specific geometry types as defined in ISO 19107. For example, 3D surfaces could be represented in a dataset using 3D polygons or 3D meshes such as triangulated irregular networks (TINS) or by non-uniform rational B-spline surfaces (NURBS).

In order to improve interoperability and facilitate implementation, this profile restricts to the use of 3d polygons and 3d meshes.

==== Implicit Geometry

Geometry shall be explicitly defined and may not be implicit.

=== CRS

All CityObjects shall use the same CRS.

The coordinate reference system (CRS) shall be defined as a URL formatted according to the OGC Name Type Specification:

http://www.opengis.net/def/crs/{authority}/{version}/{code}

where {authority} designates the authority responsible for the definition of this CRS (usually "EPSG" or "OGC"), and where {version} designates the specific version of the CRS ("0" (zero) is used if there is no version).

A projected, cartesian coordinate system shall be used.

== Conformance Class Abstract Test Suite (Normative)

NOTE 1:    Ensure that there is a conformance class for each requirements class and a test for each requirement (identified by requirement name and number)

=== Conformance Class A

==== Requirement 1

Requirement 1
Test purpose	Verify that…​
Test method	Inspect…​

==== Requirement 2

== Title ( {Normative/Informative} )

NOTE 2:    Place other Annex material in sequential annexes beginning with "B" and leave final two annexes for the Revision History and Bibliography

== Revision History

Date	Release	Editor	Primary clauses modified	Description
2016-04-28	0.1	G. Editor	all	initial version

== Bibliography

NOTE 3:    The TC has approved Springer LNCS as the official document citation type.

Springer LNCS is widely used in technical and computer science journals and other publications

• For citations in the text please use square brackets and consecutive numbers: [1], [2], [3]

– Actual References:

[n] Journal: Author Surname, A.: Title. Publication Title. Volume number, Issue number, Pages Used (Year Published)

• [], OGC: OGC Testbed 12 Annex B: Architecture (2015).